Quasicrystal

Atomic model of fivefold icosahedral-Al-Pd-Mn quasicrystal surface.

Quasiperiodic crystal (quasicrystal) is crystalline structure that is ordered but aperiodic, having no translational symmetry — which is to say, non-repeating patterns. Such structure had been described mathematically, including by Roger Penrose, prior to being discovered in nature by Daniel Shechtman.

Reading

• The Crystal Gazer, frontline.in, http://www.frontline.in/stories/20111118282311400.htm  — introduction to quasicrystals and Shechtman
• Impossible Crystals Snag Chemistry Nobel, nature.com, 2011-11-05, http://www.nature.com/news/2011/111005/full/news.2011.572.html